Hydrodynamic fluid film bearing and bearing housing with cooling capacity

ABSTRACT

A hydrodynamic fluid film bearing for supporting a rotation shaft of a turbo or rotary apparatus includes a sleeve having a circular inner opening for receiving a rotation shaft therein, at least one metallic foil member of arc shape having one end fixed to the inner surface of the sleeve and arranged along the inner opening of the sleeve, and at least one elastic member disposed at the sleeve between the sleeve and the foil member. A bearing housing for receiving a bearing of a rotary apparatus is further provided, in which the bearing housing includes a circular opening for receiving the bearing therein, and the circular inner opening of the bearing housing includes grooves for cooling air passage formed at regular interval in the axial direction on the inner surface of the bearing housing. The bearing received in the bearing housing is preferably a hydrodynamic fluid film bearing.

REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. Pat. application Ser. No.11/168,618 filed on Jun. 27, 2005, now U.S. Pat. Ser. No. 7,374,342which claims priority of Korean Patent Application Nos. 10-2004-0058365,filed on Jul. 26, 2004, and No. 10-2004-0058797, filed on Jul. 27, 2004,in the Korean Intellectual Property Office, the entire contents of whichare incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a cooling system for a turbo or rotaryapparatus, more particularly, to a hydrodynamic fluid film bearing, anda bearing housing containing a bearing therein for a turbo or rotaryapparatus, in which the bearing includes foil members and/or coolingpassages such as grooves formed about the bearing for effectivelycooling the bearing or rotator shaft of the apparatus.

BACKGROUND OF THE INVENTION

A hydrodynamic fluid film bearing is known in the art, which istypically used to support a rotor shaft in a turbo or rotary machinesuch as a compressor, a blower, a motor, a generator, and other rotaryapparatus or the like. Contrary to a conventional ball bearing or ajournal bearing for supporting a rotor shaft, which typically uses anoil film as a lubricant and cooling medium for the rotor, thehydrodynamic fluid film bearing for a rotor shaft utilizes a highpressure air layer between the bearing and the rotor shaft. Thehydrodynamic fluid film bearing is effective to support a rotor inparticular for a small sized and light weighted turbo apparatus, whichrotates at a high speed of 50,000 RPM to 150,000 RPM, for example.

FIG. 1 is a sectional view of one example of a conventional hydrodynamicfluid film bearing for supporting a rotor with an air layer formedbetween the bearing and the rotor for cooling heat generated in theapparatus.

Referring to FIG. 1, the hydrodynamic fluid film bearing of this typehas a sleeve shape, and a rotation shaft 1 is received in a hollow innerspace of the hydrodynamic fluid film bearing. When the rotation shaft 1rotates, a gap G of typically 3 to 10 μm is formed between a bearingsleeve 20 and the rotation shaft 1. Because the rotation shaft 1 rotatesin high speed with the fine gap G formed between the bearing sleeve 20and the rotation shaft 1, a large amount of heat generated between thebearing sleeve 20 and the rotation shaft 1 cannot effectively bedischarged from the apparatus.

To address this concern, various attempts have been made in whichcompressed air is forced into the gap G between the bearing sleeve 20and the rotation shaft 1 for passing through the gap G in order todissipate the heat. However, the compressed air circulating through thefine gap G cannot often effectively dissipate the overheating caused byhigh speed rotation of the rotation apparatus.

FIG. 2 is a sectional view of another example of a known hydrodynamicfluid film bearing. Referring to FIG. 2, hydrodynamic fluid film bearing10 includes a sleeve 11 having a circular inner cavity 12 in which arotation shaft 1 is rotatably received, and elastic metal foils 21arranged at the hollow cavity 12 between the sleeve 11 and the rotationshaft 1.

The elastic metal foils 21 are arranged on the inner wall surface of thesleeve 11 typically partially overlapping one another. In this manner,one end of each metal foil 21 is fixed to an inner surface 11 a of thesleeve 11 and the other end, which overlaps with an adjacent metal foil21, generally contacts with the outer surface of the rotation shaft 1.As shown in the figure, the metal foil 21 can be fixed to the sleeve 11with one end of the metal foil 21 inserted in a slot 13 formed on theinner surface 11 a of the sleeve 11 and fixed with a fixing member 22 inthe slot 13.

When the rotation shaft 1 rotates in the hollow opening 12 of the sleeve11 at a certain speed, an air layer of high pressure is formed betweenthe rotation shaft 1 and the metal foils 21. The rotation shaft 1 floatsin the air due to the air pressure and rotates while maintaining auniform distance from inner surface of the sleeve 11. Here, the metalfoils 21 operate typically as a damper in supporting the rotation shaft1.

However, if the rotation shaft 1 vibrates or trembles severely due to anexternal impact, for example, the rotation shaft 1 may be pushed againstthe metal foils 21 of the sleeve 11, causing damages to the sleeve 11and the foils 21.

In order to solve such a problem, the metal foils may be overlapped oneanother to form multi-layered metal foils. However, such metal foils aretypically not effective to provide adequate damping properties orsupports to the rotation shaft in the presence of severe externalimpacts.

SUMMARY OF THE INVENTION

The present invention provides a cooling system for a turbo or rotaryapparatus, in which the cooling system comprises a cooling structureadapted to provide an adequate cooling performance to a bearing of therotary apparatus, especially for the bearing generating a large amountof heat in the bearing by rotation of a rotation shaft received in thebearing such as an hydrodynamic fluid film bearing. The presentinvention further provides a bearing housing for providing an adequatecooling performance to a bearing retained therein. The present inventionalso provides a hydrodynamic fluid film bearing for supporting arotation shaft therein, in which the bearing can provide adequatedamping properties and effectively support the rotation shaft even whenit is subject to severe external impacts.

According to one aspect of the present invention, a hydrodynamic fluidfilm bearing for a rotary or turbo apparatus comprises: a sleeve havinga circular inner opening for receiving a rotation shaft therein, atleast one foil member having one end fixed to the inner surface of thesleeve and arranged along the inner opening of the sleeve, and at leastone elastic member disposed at the sleeve between the sleeve and thefoil member.

The hydrodynamic fluid film bearing preferably includes a cooling grooveformed at the inner surface of the sleeve along the elastic member. Theelastic member of the hydrodynamic fluid film bearing has an end portionprotruding toward the inner opening of the sleeve.

The hydrodynamic fluid film bearing preferably comprises a plurality offoil members arranged along the inner opening of the sleeve withportions of the foil members partially overlapping with one another. Thefoil members are preferably formed of metal, having a generally arcshape.

The elastic member is preferably fixed to the sleeve with a supportmember engaged there-between, with the support member securing a lowerportion of the elastic member. The elastic member has a viscous propertyto endure a shearing force applicable to the elastic member by therotation shaft. The elastic member advantageously includes a coveringmember of abrasion resistance property disposed on an upper surface ofthe elastic member.

According to one aspect of the present invention, a bearing housing forreceiving a bearing of a rotary apparatus, comprises a circular openingfor receiving a bearing and thereby defining a circular inner surface inthe bearing housing, wherein the circular inner surface includes groovesfor air passage formed at regular interval on the inner surface of thebearing housing.

The grooves of the bearing housing are preferably formed in thelongitudinal direction of the bearing housing. The bearing housingpreferably includes a plurality of key grooves formed at one end of thebearing housing to support a tangential force generated by the rotationof a rotation shaft of the rotary apparatus when the bearing housing isassembled with the rotary apparatus. The bearing housing may furtherinclude a flange for connecting the bearing housing to an externalstructure of the rotary apparatus.

The bearing in the bearing housing is preferably a hydrodynamic fluidfilm bearing.

According to still another aspect of the present invention, a coolingsystem for reducing heat in a bearing of a rotary apparatus comprises: abearing housing having a circular opening for receiving a bearingtherein, and grooves for air passage formed on the inner surface of thebearing housing in a generally axial direction of the bearing housing,in which the groves for air passage are configured to pass compressedair for reducing heat in the bearing.

The bearing of the cooling system is preferably a hydrodynamic fluidfilm bearing, and the hydrodynamic fluid film bearing is configured toreceive a rotation shaft of the rotary apparatus, in which the rotationshaft rotating in the bearing includes an air gap defined between therotation shaft and the bearing, and the air gap is further configured topass the compressed air there-through.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will become more apparent by exemplary embodiments thereofdescribed in detail with reference to the attached drawings in which:

FIG. 1 is a sectional view of one example of a conventional hydrodynamicfluid film bearing having an air gap formed therein through whichcompressed air flows;

FIG. 2 is a sectional view of another example of a conventionalhydrodynamic fluid film bearing with metallic foils affixed therein;

FIG. 3 is a perspective view of a hydrodynamic fluid film bearingaccording to one embodiment of the present invention;

FIG. 4 is a sectional view of the hydrodynamic fluid film bearing, takenalong the line IV-IV of FIG. 3;

FIG. 5 is a perspective view of a portion of the hydrodynamic fluid filmbearing of FIG. 3 showing the details of an elastic member;

FIG. 6 is a perspective view of a bearing housing for a hydrodynamicfluid film bearing according to another embodiment of the presentinvention;

FIG. 7 is a front view of the bearing housing for a hydrodynamic fluidfilm bearing, taken from direction “VII” of FIG. 6 and further showing ahydrodynamic fluid film bearing assembled in the bearing housing; and

FIG. 8 is a sectional view of the bearing housing for a hydrodynamicfluid film bearing, taken along the line VIII-VIII of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3 is a perspective view of a hydrodynamic fluid film bearingaccording to one embodiment of the present invention, and FIG. 4 is asectional view of the hydrodynamic fluid film bearing according to theembodiment taken along the line IV-IV of FIG. 3.

Referring to FIGS. 3 and 4, hydrodynamic fluid film bearing 100according to this embodiment includes a bearing sleeve 110 for receivinga rotation shaft 101 therein, and plural metal foils 120 fixedlyarranged between the sleeve 110 and the rotation shaft 101.

The sleeve 110 is formed in a circular shape having a circular opening111 for receiving the rotation shaft 101 therein. The diameter of thehollow opening 111 is larger than the diameter of the rotation shaft 101for displacing an inner surface 110 a of the sleeve 110 from an outercircumference 101 a of the rotation shaft 101, which rotates within thecircular opening 111.

A plural number of metal foils 120 are fixed along the circular opening111 of the sleeve 110. The metal foils 120 have an elasticcharacteristic to operate as a damper or a sliding guide for slidablysupporting the rotation shaft 101, and the metal foils 120 are formed ina plate or sheet-like shape to reduce heat and abrasion caused byrubbing against the rotation shaft 101. A coating material is preferablycovered on the metal foils 120 for making them slide smoothly on therotation shaft 101 and reducing abrasive frictions there-between.

In order to improve the damping and sliding performance of the metalfoils 120, the metal foils 120 are bent generally in an arc shape havinga curvature with their free ends approaching to the proximity of or incontact against the outer surface of the rotation shaft 101. As shown,one end of each metal foil 120 is fixed to the inner surface 110 a ofthe sleeve 110 in the circular opening 111 while the other end of themetal foil 120 is displaced from the inner surface 110 a of the sleeve110.

In order to fix the metal foils 120 to the inner surface 110 a of thesleeve 110, slots 112 are formed along the inner surface 110 a of thesleeve 110 with intervals. One end of each metal foil 120 is bent at anangle and inserted in the slot 112, and a fixing member 121 is press fitin the slot 112 for firmly fixing the end of the metal foil 120 at theslot 112. As a result, the metal foil 120 is securely affixed to theinner surface 110 a of the sleeve 110. However, the metal foils 120 canbe connected to inner surface of the sleeve 110 in other manners knownin the art.

The length of the metal foils 120 extending in the circumferentialdirection is preferably set to partially overlap with the fixed ends ofadjacent metal foils 120 for enhancing the efficiency and function ofthe bearing.

According to one preferred embodiment of the present invention, at leastone elastic member 130 is disposed along the inner surface 110 a betweenthe sleeve 110 and each of the metal foil 120. The elastic member 130 isformed of a resilient and elastic material for providing cushioningsupports to the metal foils 120, and preferably has a viscosity of forproviding a dynamic stability against a shear force, in particular.Thus, the elastic member 130 (which is preferably viscous) caneffectively support the metal foils 120 while elastically transformingits shape when impacts are applied onto the metal foils 120. An exampleof the viscous and elastic member 130 includes a polymer material formedof acryl.

When an external impact is applied to the rotation shaft 101 to tremblethe rotation shaft 101, the impact is transmitted to the metal foils 120and the outer surfaces of the metal foils 120 contact the viscous andelastic members 130. Thus, the viscous, elastic members 130 can absorbthe impact effectively.

More specifically, referring to FIG. 5, the viscous and elastic member130 having a suitable dimension is arranged in the longitudinaldirection of the sleeve 110, with one side of the viscous and elasticmember 130 securely fixed at the inner surface 110 a of the sleeve 110.In order to fix the elastic member 130 to the inner surface 110 a of thesleeve 110, a slot 113 is formed on the inner surface 110 a of thesleeve 110 in the longitudinal direction of the sleeve 110, and asupport member 131 is securely engaged between the elastic member 130and the slot 113. The support member 131 may surround a lower (i.e.,outer) portion of the elastic member 130 for securing it. Due to thesupport member 131, the elastic member 130 can be securely affixed tothe sleeve 110 and maintain its shape. However, the support member 131may be omitted, and the elastic member 130 can be received directly inthe slot 113.

With the lower side of the elastic member 130 fixed in the slot 113, theupper side of the elastic member 130 is protruding out from the slot 113toward the outer surface of the metal foil 120. The height of theelastic member 130 is set to be protruding to a certain degree towardthe center of the sleeve 110 from the inner surface 110 a of the sleeve110, in order to provide suitable cushioning supports to the metal foils120.

A covering member 132 may optionally be disposed on the upper surface ofthe elastic member 130 for protecting and covering the contact surfaceagainst the outer surface of the metal foil 120. The covering member 132on the elastic member may be formed of a hard coating material ofabrasion resistance, a heat-resistant film material, or other coatingmaterials having suitable property.

The width of the protruding end portion of the elastic member 130 may besmaller than the width of the opposite end portion fixed in the slot 113for elastic member, with the sectional shape of the elastic member 130formed in a trapezoidal configuration. As a result, the elastic member130 is prevented from escaping from the sleeve 110 even when arotational (shearing) force is applied to the elastic member 130. Inaddition, since the area of the lower surface of the elastic member 130is larger than the area of the upper surface, it may provide adequatecushioning supports to the metal foils 120. However, the sectional shapeof the elastic member can be varied.

Because the elastic members 130 are placed at the sleeve 110 below themetal foils 120, heat is not transmitted from the metal foils 120 to theelastic members 130 under the normal operating condition. Therefore, theintrinsic characteristics and shape of the elastic member 130 can bemaintained without damaging from the excessive heat.

In addition, it is more advantageous to make the elastic member 130 becooled to a temperature lower than a threshold temperature not to bedamaged by heat. In order to meet this concern, a cooling groove 140 isformed at the inner surface 110 a of the sleeve 110 along the lateralsides of the elastic member 130 in the longitudinal direction. Morespecifically, the groove 140 is formed with a suitable width and depthand in parallel relation with the longitudinal direction of the slot113, at both sides of the elastic member 130 including the area of theelastic member receiving slot 113. The grooves 140 operate as a coolingchannel through which air can circulate for cooling the metal foils 120and the sleeve 110. Accordingly, the elastic members 130 located in thecooling channel can be cooled to a temperature lower than a thresholddegree. Thus, the shape and characteristics of the elastic member 130can be maintained for an extended period of time.

The operation of the hydrodynamic fluid film bearing 100 according tothe above-described embodiments of the invention is now describedherein.

First, when the rotation shaft 101 rotates within the circular opening111 of the sleeve 110 at a certain speed, an air layer of high pressureis formed between the rotation shaft 101 and the metal foils 120. Due tothe high pressure of the air layer, the rotation shaft 101 rotates whilefloating in the air and maintaining a predetermined distance from themetal foils 120. During the rotation of the rotation shaft 101, themetal foils 120 are functioning as a damper and/or a cushioning guide,and prevent the rotation shaft 101 from directly contacting against theinner surface 110 a of the sleeve 110. In addition, because the elasticor cushioning members 130 are placed at the inner surface 110 a of thesleeve under the metal foils 120, the rotation shaft 101 is furtherprevented from directly contacting against the inner surface 110 a ofthe sleeve 110, even when the rotation shaft 101 trembles by an externalimpact applied to the rotation shaft and pushing it to the metal foils120. Accordingly, the rotation shaft 101 can rotate stably and withoutdamaging the metal foils 120 or the sleeve 110.

FIG. 6 is a perspective view of a bearing housing constructed accordingto one embodiment of the present invention. Referring to FIG. 6, abearing housing 30 includes a bearing accommodating or housing unit 32having a hollow opening 31 for receiving a bearing therein, and a flange34 disposed around the circumference of the bearing accommodating unit32.

The flange 34 is formed preferably in a circular shape, and hasconnection holes 35 formed around the flange 34 for connecting thebearing housing 30 with an external housing or suitable structure (notshown) of a rotary or turbo apparatus, such as a compressor, blower,motor, generator, or the like, which contains a rotor (e.g., therotation shaft 101) rotating at a high speed. The connection holes 35may be symmetrically formed along the circumference of the flange 34with a uniform interval in order for the bearing housing 30 to evenlysupport the load when the bearing housing 30 is structurally connectedwith the external housing of the rotary apparatus. The shape of thebearing housing is not limited to a circular shape as shown in FIG. 6,and can be varied according to the shape of the external housing orstructural member of the rotary apparatus to be combined and/or thelocation of a rotation shaft.

Spline key grooves 36 may be formed at a distal end of the bearingaccommodating unit 32 of the bearing housing 30, for using whenconnecting with the external housing to support the rotational power.

FIGS. 7 and 8 are sectional views illustrating the assembled state of abearing with the bearing accommodating unit 32 of the bearing housing,with a rotation shaft of the rotary apparatus received in the bearing,constructed according to one embodiment of the present invention. Morespecifically, FIG. 7 illustrates a front view taken from the directionVII of FIG. 6, and FIG. 8 illustrates a sectional view taken along theline VIII-VIII of FIG. 6. Here, a conventional hydrodynamic fluid filmbearing (without having metal foils affixed therein) is used for thebearing. However, the bearing is not limited to the particular types ofthe bearings as shown in the figures, and the hydrodynamic fluid filmbearings of the invention shown in FIGS. 3 and 4, for example, can bealso used for the bearing.

Referring to FIGS. 7 and 8, a plurality of air passages 33 (in form ofgrooves) are formed along the inner surface of the bearing accommodatingunit 32. Since compressed air is supplied from an external compressedair source (not shown) to the air passages 33, the heat generated at thebearing 20 due to the rotation of the rotation shaft 1 in the bearing 20can effectively be dissipated with the air. In addition, compressed airis also supplied to pass through air gap G provided between the innersurface of the bearing 20 and the rotation shaft 1 as described before.As a result, the compressed air passes through the air passages 33formed along the outer surface of the bearing 20 and the air gap Gformed at the inner surface of the bearing 20 at the same time, thusimproving the cooling performance of the bearing housing.

The compressed air can be supplied by an external compressed airsupplier source, or it can be supplied by utilizing the rotational forceof the turbo or rotary apparatus in a manner to be contemplated by theperson skilled in the art. For instance, in a turbo apparatus such as acompressor or a blower having a hydrodynamic fluid film bearing and arotation shaft retained in the bearing housing of the present invention,the bearing can be located between an air inlet unit and an air outletunit of the turbo apparatus. In this case, the compressed air can flowthrough the air channels formed the inner surface and outer surface ofthe bearing (such as bearing 20) as described above without providing anadditional compressed air supplier. As a result, the cooling mechanismof such a bearing can be provided at a comparably low cost.

According to an experiment, in which a rotation shaft was received in aconventional hydrodynamic fluid film bearing (as shown in FIG. 1), andthe rotation shaft was rotated at a speed of 60,000 to 100,000 rpm whilesupplying compressed air through the gap G of 3 to 10 μm formed betweenthe shaft and the bearing, the temperature of the bearing went up toabout 200° C. after a set period of time. However, according to thepresent invention, when utilizing the above-described cooling structureadopted in the bearing housing of the invention, the temperature of thebearing became about 150° C. after the same period of time, which is atemperature about 25% lower than that of the conventional coolingstructure discussed above.

Referring again to FIGS. 7 and 8, the bearing 20 can be connected to thecircular opening of the bearing accommodating unit 32 of the bearinghousing 30 with a tolerance between the bearing housing 30 and thebearing 20 being smaller than the gap between the bearing 20 and therotation shaft 1 in the rotating state, or it can fixed thereto withpress-fit or lose-fit.

As described above, when the hydrodynamic fluid film bearings are usedas the bearing 20, the compressed air is supplied to the gap G while therotation shaft 1 is rotating, and at the same time the compressed air isalso supplied through the air passages 30, in order to effectivelyreduce the heat generated at the bearing 20 by rotation of the rotationshaft 1 received therein. However, when other bearings than thehydrodynamic fluid film bearing are used for the bearing 20, thecompressed air can optionally be supplied only through the air passages33, but not through the gap between the bearing 20 and the rotationshaft 1, in order to reduce the heat.

In addition, because the sidewall portions of the air passages grooves33 contact with the bearing 20, they can function as cooling fins, andthus further improve the cooling performance of the bearing.

According to the invention as described above, elastic (and preferablyviscous) members are positioned at the inner surface of the sleeve, thusan external impact applied to a rotation shaft can be absorbedeffectively. In addition, since cooling passages are formed along theelastic members, the elastic members can maintain their designed shapeand characteristics and be useable over an extended period of timewithout losing their intended property. Accordingly, the rotationstability of the rotation shaft is improved.

In addition, a bearing housing having air passages and/or gaps fordelivering compressed air along the bearing is provided in order toefficiently dissipate the heat, generated form rotation of the rotationshaft, from the inner surface and the outer surface of the bearing.Portions of the inner surface of the bearing retaining housing contactthe outer surface of the bearing to operate as cooling fins, thus thecooling efficiency can further be improved.

Furthermore, according to one embodiment of the present invention, acompressed air source used in a rotary or turbo apparatus can also beused as a compressed air source in a cooling structure, thus anadditional compressed air provider is not necessarily required.

While the present invention has been particularly shown and describedwith reference to exemplary or preferred embodiments thereof, it will beunderstood by those of ordinary skill in the art that various changes inform and details may be made therein without departing from the spiritand scope of the present invention as defined by the following claims.

1. A bearing housing for receiving a bearing of a rotary apparatustherein, the bearing housing comprising a circular opening for receivinga bearing and thereby defining a circular inner surface in the bearinghousing, the circular inner surface including grooves for air passageformed at regular interval on the inner surface of the bearing housing,wherein a plurality of key grooves are formed at one end of the bearinghousing to support a tangential force generated by the rotation of arotation shaft of the rotary apparatus when the bearing housing isassembled with the rotary apparatus.
 2. The bearing housing of claim 1,wherein the grooves for air passage are formed in the longitudinaldirection of the bearing housing.
 3. The bearing housing of claim 1,further comprises a flange for connecting the bearing housing to anexternal structure of the rotary apparatus.
 4. The bearing housing ofclaim 1, wherein the bearing is a hydrodynamic fluid film bearing.
 5. Acooling system for reducing heat in a bearing of a rotary apparatus, thecooling system comprising: a bearing housing having a circular openingfor receiving a bearing therein; and grooves for air passage formed onthe inner surface of the bearing housing in a generally axial directionof the bearing housing; wherein the grooves for air passage areconfigured to pass compressed air for reducing heat in the bearing;wherein a plurality of key grooves are formed at one end of the bearinghousing to support a tangential force generated by the rotation of arotation shaft of the rotary apparatus as the bearing housing isassembled with the rotary apparatus.
 6. The cooling system of claim 5,wherein the bearing is a hydrodynamic fluid film bearing.
 7. The coolingsystem of claim 6, wherein the hydrodynamic fluid film bearing isconfigured to receive a rotation shaft of the rotary apparatus, therotation shaft rotating in the bearing with an air gap defined betweenthe rotation shaft and the bearing, the air gap is further configured topass the compressed air there-through.